Harry Potter producer David Heyman has revealed that the upcoming spin-off, Fantastic Beasts And Where To Find Them, will be "very special".

The 52-year-old, who produced all eight instalments of JK Rowling's wizarding series, admitted details for the film, inspired by the Hogwarts textbook, is being kept under wraps.

He told Comingsoon.net: "I can't talk really about it yet. All I can say is that it's great."

"Jo [JK] had no need to go back to this universe or world. It's not Harry Potter per se, but the world of Harry. She's chosen to do so because she felt a need to tell a story."

The author will make her screenwriting debut for the film, which would focus on the book's fictitious author Newt Scamander.

"That she's doing it means that it's going to be very, very special," David added.

The project was announced on September 13, and JK said: " I would only revisit the wizarding world if I had an idea that I was really excited about and this is it."

Daniel Radcliffe, whose film career was launched after he played boy wizard Harry in the films, has already ruled out appearing in the new movie, which the writer has said will not be prequels or sequels to Harry's story.

"Although it will be set in the worldwide community of witches and wizards where I was so happy for 17 years, Fantastic Beasts And Where To Find Them is neither a prequel nor a sequel to the Harry Potter series, but an extension of the wizarding world. Newt's story will start in New York, 70 years before Harry's gets under way," she said.